In the prior art, there is a known SAW filter which, by taking advantage of surface acoustic waves (SAW) which are transmitted along the surface of a piezoelectric material such as, for example, quartz or the like, eliminates noise by only allowing to pass a frequency signal of a predetermined frequency band.
With this kind of SAW filter, it is possible to obtain a higher attenuation characteristic as compared to quartz by including a piezoelectric material such as, for example, langasite (La3Ga5SiO14) or the like, which has a crystalline structure just like that of quartz.
However, with a SAW filter according to the prior art such as the one described above, it sometimes happens that the attenuation characteristic undesirably deteriorates, according to the structure of the printed substrate upon which it is mounted, and there is a fear that it may no longer be possible to obtain the desired attenuation characteristic.